Am I just being to nice?

There's this woman I know, she is about 10 years older than me, and she has befriended me through a mutual friend. When I met this woman through the mutual friend, I was nice as normally one would be when introduced to a friends "friend". Anyway, this woman asked for my phone number and my email address and then eventually began calling me more often than she would call our mutual friend. Our mutual friend is currently relieved that this woman is finally leaving her alone and her life has returned to normal, but now I am being bombarded with emails and constant phone calls...not just at home but on my cell phone and at work. This woman constantly wants to get together for dinner or lunch or both in the same day or wants to go to movies, out of town trips or just spend the weekend together. I swear its almost like she is in love with me. Only I think she acts this way because she is codependent and can't have normal relationships with people. I just need room to breathe and I have asked her nicely to not call so many times in a day. So she has reduced the phone calls but increased the emails. If I don't respond to the emails or return a phone call, then she gets upset and calls me and bawls me out for being impolite and not returning calls. Its not like I don't have a life of my own...even if I did, she makes it nearly impossible to enjoy any of it. How can I get my message to this woman that I am busy without having to deal with a 20 minute lecture on returning phone calls? I know if I tell this woman to take a hike then she will just go back to bothering our mutual friend. The mutual friend is actually enjoying the break, though she feels badly that I am now in her same predictament. Am I just being too nice? This woman wouldn't have even known me if my friend (our mutual friend) never introduced us. Help...what can I do to get my life back?